The present invention relates generally to a line head and an imaging apparatus incorporating the same, and more particularly to a line head wherein a micro lens array is used to project a row of light emitter devices onto an application plane to form a row of imaging spots and an imaging apparatus using the same.
So far, Patent Publication 1 has come up with an optical write line head wherein multiple LED array chips are located in an LED array direction, and the LED array of each LED array chip is projected and magnified through a correspondingly located positive lens onto a photosensitive member, so that images of light emitting dots at the ends of the LED array chips adjacent to one another on the photosensitive member are formed adjacently at the same pitch as the inter-image pitch of the light emitting dots of the same LED array chip, and an optical read line head with the optical path reversed.
Further, Patent Publication 2 has proposed an optical write line head wherein two rows of LED array chips are arranged at a spacing, and two rows of positive lens arrays, each having a positive lens corresponding to each LED array chip, are arranged at a repetitive phase that is a half period off, so that images of light emitting dot arrays are lined up on a photosensitive member.
Patent Publication 1
JP(A)2-4546
Patent Publication 2
JP(A)6-278314
In such prior arts, if the image plane budges forth and back in the optical axis direction of the lens due to vibrations, etc. of the photosensitive member, there is then a displacement of the light emitting dots on the photosensitive member, which otherwise gives rise to a variation in the pitch between scan lines drawn by the relative movement of the light emitting dot array in the subordinate scan direction (a pitch variation in the main scan direction. The same can be said of even when images of the light emitting dot array are in alignment with one another on an ideal image plane.
In view of such problems with the prior art as described above, one object of the present invention is to provide an optical write line head comprising a row of light emitter devices lined up corresponding to each of multiple positive lenses arranged in array form, wherein even with the write plane fluctuating in the optical axis direction, there is none of variations resulting from displacements of light emitting dots.
Another object of the invention is to provide an imaging apparatus incorporating such an optical write line head, and an optical read line head with the optical path reversed.